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.go to the other, a little at atime, shaking well the formed--will notanswer.

{.INITE STATES THOMAS C. ROCHE, OF BROOKLYN, ASSIGNOR TO E. 86 H. T.ANTHONY & G

.. OF NEW YORK, N. Y.

PHOTOGRAPHIG PAPER.

, SPECIFICATION forming part of Letters Patent No. 241,070, dated -May3, 1881 Application filed February 8, 1881. (No specimens.)

To all whom it may concern: latter at each addition. I then put thebottle Be it known that l, THOMAS C. Room-1, of now containing theunited solutionsinto stemthe city of Brooklyn,- in the county of Kingsered light-excluding vessel containing water, and State of New York,have invented a new the temperature of which is raised and kept up anduseful Improvement in Photography, of to between 80 and 110Fahrcuheitfor two or which the following is a specification. three days,occasionally shaking the bottle, so One of the comparativelyniodern'improveas to keep the contents thoroughly mixed.mentsinthenrtofnegativephotographicpriut- ,Each days cooking makes thesolution more big consists in the successful use of gelatine sensitive.I can,'by raising the temperature to sensitized by a bromide of silverapplied as a the boiling-point and maintaining it fora short coating tothe glass plate forreceiving the negtime-say one totwo hou'rs'-acc0mplish nearly ative photographieimpression,asensitized gel thesame result; .but I prefer the efi'ect the atine solution having beendiscovered and procooking more slowly produces. After the soducedwhiclnwhen thus employed in negative lntion has been thus cooked pour itinto a 5 printing, is possessedot' suchextreme sensisuitabledish-preferably glass or porcelaiu-- tiveness as to enable a satifactory'photoand permit it to cool and set. Ithen divideit graphicimpression to be secur d very quickly, up into smallpieces and put itinto a suitable and even by a feeble artificial light; but sofar holderfor washing-a coarse canvas bug or an as I am aware'the use of thisgelatine solution earthen vessel with perforations in the bottom.

.0 has been hitherto confined to negative print- I then allow cold waterto run onto it fora few 7o ing, and has not, until my present-invention,hours, occasionally stirringup the massto wash been successfully, if atall, employed in pos'i-' out all soluble matter, such as nitrate ofamtive printing. It is possible that. a gelatine mania and excessof-bromide, if any remain. solution may have been laid upon paper; bntitI then dissolve the gelatine thus prepared by so the paper has. beenemployed only as a heatand add toitabout an equal quantity, by 5 tissueon which to form a. pellicle intended fluid weight, of water, thusforming a solution to he removed and used as a negative. I have thatcontains no free nitrate of silver, and thatsucceededincombiningagelatiue solution senis much thinner than issuitable forjuse on sitized with a neutral bromide of silver with platesfor negative printing. It is essential o photographic paper,whereonpositive photoin negative printing that the solution should 8ographs may be successfully taken under a be snificieutly concentrated toform a comparnegative almost instantaneously, and even atively thick andopaque film on the plate.

by the light eta common oil-lamp. When thus concentrated it will notanswer to lwill proceed to describe my method of thus apply to paper forpositive printing. In the 35 combining sensitized gelatine with paper.latter it is essential that the sensitized gela- 8 5 y The solution Iprepare is as follows: I put tine shall be applied in an exceedinglythintogether in a. proper vessela glass bottle prefilm, and that it, insome measure,.penetrate i'erred-ot' good gelatine, (preferably Frenchand become incorporated with theorganic inatgelatine,)say,onehundred andfifty grains, broter of the paper. l

4 0 mide of ammonia sixty grains, and water five The solution being thusprepared, it is ready go ounces. When the gelatine has softened I putfor use on paper; but now it is necessary to thebottlejn a water-bathand raise the temhave regard to the condition of the paper to peraturesufliciently to dissolve'the gelatine which it is to be applied, Papersuitable for say to '90 or Fahrenheit. In another tissues-that is, paperthe pores or interstices 4 5 bottle I dissolve, say, one hundred grainsof of which have been filled with some prep- 5 nitrate of silver in fiveounces of water, and aration that prevents the gelatine solution then ina room in which there is only non-actinic from penetrating the surfaceof the paper and light I mix the contents of the two bottles tocauses ittoserve the purpose of a simple tabgether by adding the silver solutiongradually let or plate on which a removable pellicie is It must becommon reg 2 V anew unprepared or unfilled photographic paper as itcomes from thdmanufacturer. If it is entirely unsized and merelycalendered, all the better. I take paper such asI have described,

5 and apply the solution either by flowing; itv

over the paper, by floating the paper. on the solution, orin any othersuitable manner. The

paper is then, hung up and allowed to dry, wnen itis-readytbr use.

1o v-All' the operations must, of course, be carriedaon. in arooi isexcluded.

from which all actinic light Paperthus-prepared, having on it no free.hnitrate of 'silyeu'will keep an indefinite time 25 ing tobring-ontg-tbe image fully.

x1 am aware ,t

suclras. Lila-V6 described has been made and used in negative printin gon plates and tissues,

except that ithas always been made and used 0 ina concentratedstate, soas to form a pellicle upon the plate or tissue, and not to penetrate orbecome combined withthe organicim'atter of. the paper. As is obvious, itis highly desirable to. be ablegto use this highly-sensitized 5gelatitre sol u tionv ;;for positive 'priifti'ng'bn' pa per; but Iain--;n'ot aware that any successful hat a solution substantiallymethodof so doing has ever been known or practiced in this country orpublished or patcute-d anywhere before my present invention. j

1 WhatIclaim as my invention,and desire to secure by Letters Patent,is-, p v 1. The methodlierein described of combining sensitized gelatiuewithpaperct'or positii e pbotographicprintingtconsisting"in firstsoftening the gelatiue ines-ater and adding the l bromide of ammonia'oran equivalentbromide, using about theproportions named; then dis solvingthe gelatine by heat and adding gradually'nit-rate of silverdissolred inwater in about the proportions named; then continuing 5 the heat atabout 80? or 100 Fahrenheit for two or three days; then, afterallowingitte cool and set, cutting it into fragments and washing out the solublematter; then tne'lting it by heat and addingaboutitsweight of water;then an 5 plyjmg it to unfilled pbotograpliic paper, into whichpenetrates, and with'th'e organic mat ter of which it combines; lastly,dryingit in any suitablemanner, allas, and for thepnrpose described. p 62. As a new-article of manufacture, unfilled. and unglazedphotographicpaper for positive. printing, with the face of which. iscombined. a sensitive substance consisting, essentially," of'gelatine'and a bromide of silver, substamj 6 tially as specified;.Witness my band this 5th dayof February,

f THOMAS OJ ROCHE. In presence otj fl. g KiilfiN G. W; VERMILYA,- HENRYErasmus.

